09 Silverado transmission problems

 have this Silverado 5.3 engine the transmission will shift from first to second no problem but when shift to 3rd its like goes into neutral if I leave up it shifts to 4th but acts like its in limp mode it is a 4 speed transmission 4X4 Im pretty sure the answer is a bad transmission it gave me no signs just happened all at once I'm adding a photo off my scanner when I shift through the gears just setting still the commanded gear will only show  first and second and no other gear when shifting through gears the transmission range switch and the IMS show correct gear I am just wondering if something electrical was wrong because the commanded gear only shows first and second or is it not to show the rest of gears? Thanks for your                                 time  

Hey there bizz2222,
Sure sounds like a bad transmission to me. I would try to shift through the gears manually while driving down the road just to see if it will grab 3rd, but really I bet it needs a rebuild or replace. Did you check the fluid for evidence of clutch material? If it's black and stinky and has no 3rd gear, I wouldn't hesitate to call it.